Declaring disaster over seems to be the only one that does not apply.
The answer is A. ATP I believe because ATP is energy and cells need energy to function so if their is no energy in the blood then the organ or organism wouldn't function properly. Hope this helped you out.
It provides exercise to the body keeping it fit and calm. Hope this helps.
My guess would be to weigh yourself before and after a workout then consume the equivalent of the amount you may have lost with water.
For example
Say you loose 2 pounds after a hour run. You should drink about 32oz to rehydrate yourself
You would start by removing anything negative of 2